Texas CDL Air Brakes Practice Test (TX) 2

4.9 out of 5 (204 votes)
80% Passing score
20 Questions
4 Mistakes allowed
Howdy, future CDL drivers! If you're gearing up for your commercial driver's license with an air brakes endorsement, you've come to the right place. Our Texas CDL air brakes practice test is designed to give you the edge you need to ace that written knowledge test. Crafted and vetted by seasoned driving instructors who have decades of experience under their belts, this test is tailored to cover all the essential topics you'll encounter on the actual CDL air brake test. This Texas DMV practice test comprises 20 multiple-choice questions that delve into crucial areas such as air brake components, their operation, safety inspections, and the ever-important stopping distance calculations. Understanding dual air brake systems is a must, as these systems ensure added safety by providing a backup in case one system fails. To pass this Texas driving test practice, you'll need to correctly answer at least 16 questions. Why choose our CDL air brake practice test? For starters, it's absolutely free. You won't have to shell out your hard-earned cash for expensive practice tests. Despite being free, our Texas drivers license practice test is packed with the same features and learning opportunities as any paid version. Each question is specifically chosen to mirror what you'll face in the real CDL test, so you're not wasting time on irrelevant material. Driving in Texas comes with its own unique set of challenges. From navigating the bustling highways of Houston to handling the vast open roads of West Texas, understanding air brake systems is crucial for safe driving. Our air brake endorsement practice test helps you prepare for these local conditions, ensuring you're ready for anything the Lone Star State throws your way. Remember, to get your commercial driver's license, you'll also need to pass the general knowledge test. Don't worry, we've got you covered there too with our comprehensive general knowledge practice tests available right here! For now, focus on mastering the Texas air brakes endorsement with our all-encompassing DMV practice test. Get ready to hit the road safely and confidently in 2026!
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Sample Texas Air Brakes Test Questions

Question 1

On some air-brake vehicles, a separate air tank can temporarily release the spring brakes. True or false?

  1. A TRUE
  2. B FALSE

Correct answer: A – TRUE

When main air pressure is lost, the spring brakes apply. Some vehicles have dual parking control valves and a separate air tank that can briefly release those brakes for emergency movement. The reserve contains enough air for only a few operations, so the movement must be planned carefully. The Texas handbook covers this feature under parking brake controls.

Source: Texas Commercial Motor Vehicle Drivers Handbook — § 5.1.15, “Parking Brake Controls”

Question 2

What is the purpose of an alcohol evaporator in an air brake system?

  1. A To introduce alcohol that reduces the risk of ice forming in the system
  2. B To increase air tank pressure above the governor setting
  3. C To eliminate the need to drain tanks that have manual drains
  4. D To remove alcohol that collects in the air tanks

Correct answer: A – To introduce alcohol that reduces the risk of ice forming in the system

An alcohol evaporator introduces alcohol into the air system to reduce the risk of ice in valves and other components during cold weather. Ice can interfere with brake operation. During cold weather, the alcohol container should be checked and filled as necessary each day. Air tanks still require daily drainage unless they have automatic drain valves.

Source: Texas Commercial Motor Vehicle Drivers Handbook — § 5.1.5, “Alcohol Evaporator”

Question 3

If normal air pressure is lost, what can a separate tank controlled by dual parking valves allow you to do?

  1. A Balance air pressure between the front and rear service brakes
  2. B Keep the vehicle parked without applying the spring brakes
  3. C Increase service-brake pressure for normal highway stops
  4. D Temporarily release the spring brakes for limited emergency movement

Correct answer: D – Temporarily release the spring brakes for limited emergency movement

Loss of main air pressure causes the spring brakes to apply. On vehicles equipped with dual parking control valves, air from a separate tank can temporarily release those brakes so the vehicle can be moved in an emergency. The separate tank permits only a few releases before its air supply is exhausted.

Source: Texas Commercial Motor Vehicle Drivers Handbook — § 5.1.15, “Parking Brake Controls”

Question 4

Air tanks with manual drain valves need to be drained only once each week. True or false?

  1. A TRUE
  2. B FALSE

Correct answer: B – FALSE

Compressed air normally contains water and some compressor oil, which collect at the bottom of the tanks. Tanks with manually operated drain valves must be drained completely at the end of each day of driving. Automatic drains expel water and oil without the same daily manual procedure, although some automatic systems also permit manual draining.

Source: Texas Commercial Motor Vehicle Drivers Handbook — § 5.1.4, “Air Tank Drains”

Question 5

When making an emergency stop, what should be your primary braking goal?

  1. A Apply the parking brake before using the brake pedal
  2. B Keep the vehicle straight while retaining the ability to steer
  3. C Lock every wheel to obtain maximum braking force
  4. D Make a sharp steering movement while braking fully

Correct answer: B – Keep the vehicle straight while retaining the ability to steer

Emergency braking should keep the vehicle in a straight line while preserving the ability to steer if necessary. In a vehicle without ABS, controlled braking or stab braking may be used as described in the handbook. If working ABS is installed on all axles, the brakes may be fully applied during an emergency stop while the driver continues steering as needed.

Source: Texas Commercial Motor Vehicle Drivers Handbook — § 5.4.3, “Emergency Stops”

Question 6

The low air pressure warning activates while you are driving. What should you do first?

  1. A Stop promptly and safely park the vehicle
  2. B Upshift to reduce engine speed
  3. C Repeatedly pump the brake pedal
  4. D Open the trailer air supply control

Correct answer: A – Stop promptly and safely park the vehicle

A low-pressure warning indicates that available braking air is dropping. Continuing to drive can leave part of the service brake system operating below full capacity and may eventually cause the spring brakes to apply. The Texas handbook directs the driver to stop right away, park safely, and have the air brake system repaired.

Source: Texas Commercial Motor Vehicle Drivers Handbook — § 5.2, “Dual Air Brake”

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